Extant research has widely studied the impact of online product review on sales and most studies have found a significant impact of these reviews as an e-WOM tool. Given the importance of the online reviews, we study a hitherto understudied area of antecedents of sentiments in user reviews. We assess the impact of contagion effect of past review sentiments on reviewers' choice to write a review. We analyze the impact of emotional response of users while writing product reviews triggered by the appraisal response to prior online reviews. A short selection of reviews, which most e-commerce websites show, along with the numerical product rating (if any) could strongly bias the sentiments in a review being written under their influence. Through a mix of experimental methods and text analysis of online reviews, we find that review writers tend to veer towards extreme reviews in absence of any benchmark or prior reviews